Flow control valve assemblies are typically used to supply/block fluids (including gases and liquids) flowing therethrough or to regulate the flow rate of fluids supplied therein. Depending on the type of control power sources employed, flow control valve assemblies are broadly classified into manual control valve assemblies opened/closed by human power and electronic control valve assemblies opened/closed by an electric force.
FIG. 1 is a cross-sectional view showing the constitution of a prior art flow control valve assembly.
As shown in FIG. 1, the flow control valve assembly comprises a pipe 1 having a flow passage through which a fluid 3 flows and formed with a plunger guide 11 on a lateral surface thereof, and a plunger 2 installed within the plunger guide 11 of the pipe 1 and moving upwardly and downwardly along the plunger guide 11 to block the flow of the fluid 3 or allow the fluid 3 to flow through the pipe 1.
Due to this configuration of the flow control valve assembly, the plunger 2 moves downwardly along the plunger guide 11 to block the flow of the fluid 3 through the pipe 1 and moves upwardly along the plunger guide 11 to allow the fluid 3 to flow through the pipe 1.
A problem of the flow control valve assembly is that when the plunger 2 actuates in a direction perpendicular to the flow of the fluid 3 to regulate the flow of the fluid 3, a large difference in the pressure of the fluid 3 at both sides of the plunger 2 is caused, which results in the occurrence of a vortex and bubbles 31 in front and in the rear of the plunger 2 to create tremendous noises. Such noises are particularly more serious in multi-residential and high-density facilities. Thus, there is a need to reduce the generation of noises from flow control valve assemblies.
Many attempts have been made to solve the above problem. For example, Korean Registered Utility Model No. 20-0360750, which was published on Sep. 1, 2004, discloses a low-noise flow control valve in which a plunger is configured to have the same spherical shape as a flow passage so that a moderate flow of a fluid is induced by the rounded shape of the flow passage to reduce the friction with respect to the fluid, which is a cause of noise generation when the flow of the fluid is regulated, and to prevent the occurrence of turbulent flow, thereby ensuring the operation of the valve with low noise generation.
The fluid gently flows at the contact surface with the plunger when the flow of the fluid is regulated to contribute to the reduction of the friction with respect to the fluid and the prevention of turbulent flow of the fluid. However, noise from the flow control valve is not completely removed and is inevitably generated to some extent.